1. Field of the Invention
The subject invention relates to a level that can be used to achieve a specified alignment between two structural elements.
2. Description of the Prior Art
A typical carpenter's level is an elongated generally rectangular structure having opposed first and second ends. Planar top and bottom faces are aligned parallel to one another and extend between the ends. The top and bottom faces are the portions of the prior art level that will be placed against another surface for assessing horizontal or vertical alignment. The prior art level also has a front face and a rear face that connect the top and bottom faces and the respective ends. The front and rear face on most prior art levels also are parallel to one another. However, the prior art does include torpedo levels that have the front and rear faces tapering towards one another in proximity to the respective ends of the level. Other prior art levels have recessed front and rear faces so that the level has a cross-section that resembles an I-beam.
A typical prior art level includes a plurality of glass tubes that are partly filled with a liquid spirit. The portion of the tube that is not filled by the liquid forms a bubble. Movement of the level will cause the liquid to gravitationally shift within the tube, and hence will cause a repositioning of the bubble. The tube includes a pair of lines that are spaced apart a distance approximately equal to the length of the bubble. When the tube is aligned horizontally, the liquid will be disposed symmetrically relative to the lines on the tube, and the bubble will be positioned precisely between the lines. The typical prior art level includes at least a first tube aligned parallel to the top and bottom faces of the level, and at least a second tube aligned perpendicular to the top and bottom faces of the level.
The prior art level can be used by placing the top or bottom face of the level on a substantially horizontal surface. The relative position of the bubble in the first tube provides an indication of the closeness of the level to a horizontal alignment. The surface on which the level is supported may be adjusted to precisely position the bubble between the lines of the first tube, and to thereby achieve a fairly exact horizontal alignment of the surface on which the level is supported.
The prior art level also may be used by positioning the top or bottom surface of the level on a substantially vertical surface. The relative position of the bubble in the second tube provides an indication of the degree of verticality of the surface against which the level is supported. The structural member against which the level is supported may be adjusted until the bubble is precisely positioned between the lines of the second tube, thereby ensuring an accurate vertical alignment.
Virtually all carpenters and home owners have at least one good quality level that is used frequently during any construction or repair project. For example, levels are used to ensure an accurate horizontal alignment of floor beams and to achieve an accurate vertical alignment of wall studs. Horizontal alignment of a structural member can be achieved more easily than vertical alignment. In particular, horizontal alignment of a beam can be achieved by merely placing the top or bottom face of the level on a substantially horizontal surface of the beam. The worker then can use both hands to adjust the relative height of one end of the horizontal beam by using shims or the like. Both hands then can be used to secure the beam in the precise horizontal orientation. Vertical alignment of a beam requires the worker to hold the level against a substantially vertical surface with one hand while the other hand is used to shift an end of the generally vertical beam. The worker may mark the position of the adjusted end of the beam on an adjacent surface once a substantially vertical alignment has been achieved. The worker then moves the level to a location where the level can be self-supporting and then uses both hands to affix the adjusted end of the beam. The worker then must check the vertical beam in this at least temporarily affixed position to ensure that the initial one-handed marking was accurate. Further adjustments may be required.
Carpenters also use squares for measuring perpendicularity of two structural members. The typical prior art square is formed from a rigid material with two legs that are precisely perpendicular to one another. The material of the prior art square typically is very thin (e.g., one-eighth inch). Each leg, however, will be approximately 1.0-2.0 inches wide. The prior art square can be used to check perpendicularity of an inside corner or an outside corner formed by two beams or other structural elements. This checking of perpendicularity of an inside corner is achieved by urging the thin outside edges of the prior art square into an inside corner between two structural elements. A perfect seating of the outside edges against the inside surfaces of the structural elements indicates precise perpendicularity. An improper fitting indicates further adjustments to one or the other of the structural elements is required.
The inside corners of the prior art level can be used in a similar manner to check the perpendicularity of an outside corner of two beams or other structural elements. In particular, the thin inside edges of the prior art square can be urged against the outside corner surfaces of the structural elements. Perfect seating of the thin inside edges of the prior art square against the surfaces of the structural elements indicates precise perpendicularity. An improper seating of the thin inside edges indicates that adjustments to one or the other structural element is necessary.
The thin perpendicularly aligned edges of a square that are used to check perpendicularity are not very stable Furthermore, the sharp outside corner of the prior art square can easily cut a worker if the square is dropped. As a result, the above-described prior art squares typically are held by the worker at all times during use and are carefully supported in a safe location when they are not being used.
Some prior art tools incorporate levels into a square. A prior art tool of this type can be used, for example, to check the horizontal alignment of the top of a door jamb and simultaneously to check the perpendicularity of the sides of a door jamb to the top member.
Some prior art squares have the respective legs of the square articulated to one another. This enables the adjustable square to achieve or measure a non-perpendicular orientation between two beams or other structural elements. For example, such an adjustable square can be used to gauge an angle between a first roof rafter and a first floor joist. The adjusted square then can be moved to other locations for either comparing the angles between other roof rafters and floor joists or for setting other such angles. Some such prior art adjustable squares include a level in one or both of the pivotally connected legs. All such prior art squares are configured to be held by the worker against an inside corner or an outside corner as in the above-described conventional fixed right angle squares. More particularly, the axis of rotation of the two legs of these prior art adjustable squares extends substantially parallel to the surfaces of the legs of the squares that are positioned against the beams or other supporting elements. Thus, achieving a selected angular orientation becomes a very difficult task with such a prior art adjustable square. The worker must manually hold the adjustable square against inside or outside corners of the structural elements being aligned and then must make any adjustments to the structural elements that may be required. The making of adjustments to the structural elements requires the worker to deposit the adjustable square at a remote location while the end of at least one of the structural element is adjusted. The worker then retrieves the adjustable square and again checks the angular alignment. This process may have to be repeated several times before a proper alignment is achieved.
The prior art also includes large, complex and costly apparatus for aligning roof rafters. These complex and costly apparatus for aligning roof rafters have few if any other uses for general carpentry.
In view of the above, it is an object of the subject invention to provide a level with plumb alignment features that enables a worker to check and achieve selected angles between two structural members.
It is a another object of the subject invention to provide an alignment apparatus that can be used to achieve a plumb or vertical alignment of one structural member relative to a second structural member.
It is an additional object of the subject invention to provide an apparatus that can be used as a conventional carpenter's level for checking horizontal and vertical alignment.
It is yet a further object of the subject invention to provide a level apparatus of approximately the same size, weight and cost as a conventional carpenter's level.